Sotagliflozin is an investigational new oral dual inhibitor of sodium-glucose cotransporters 1 and 2 (SGLT-1 and SGLT-2) which is developed by Lexicon and currently in Phase 3 clinical trial. It could be a potential treatment option for diabetics. Sotagliflozin has been shown encouraging results in exploratory (Phase 2) studies, including reduction of blood sugar, improvement in glycaemic variability, and reduced meal-time insulin dose compared with placebo in type 1 diabetics. Phase 2 studies exploring treatment in people with type 2 diabetes, including those with renal impairment, showed lowering of blood sugar, weight loss and blood pressure improvements. The chemical name of Sotagliflozin is (2S,3R,4R,5S,6R)-2-(4-chloro-3-(4-ethoxybenzyl)phenyl)-6-(methylthio)tetrahydro-2H-pyran-3,4,5-triol, and the structure is shown as formula (I):

CN101343296B disclosed the preparation of Sotagliflozin, while no crystalline information thereof was disclosed. CN102112483A (which is incorporated herein by reference) disclosed anhydrous crystalline Form 1 and crystalline Form 2 (herein after briefly named as existing crystalline Form 1 and existing crystalline Form 2). The inventors of the present disclosure have found it difficult to repetitively prepare the existing crystalline Form 1. Although it's easier to repetitively prepare the existing crystalline Form 2 compared with Form 1, crystalline Form 2 is not stable under high water activity. Meanwhile, it is also found that the existing crystalline Form 2 has poor stability after grinding, and crystal transformation is easy to occur in the formulation preparation process. The existing crystalline Form 2 also has drawbacks such as wide particle size distribution, uneven particle size distribution and the like, which make it not beneficial to the post-treatment of drug development.
Novel crystalline forms (including anhydrates, hydrates and solvates) of the active pharmaceutical ingredients may provide more solid forms in the formulation, and may also offer processing advantages and better physicochemical properties. The processing advantages include processability, purification ability or serving as intermediate crystal forms to facilitate solid state transformation to desired forms. The better physicochemical properties include bioavailability and stability. For certain pharmaceutical compounds, the novel crystalline forms can also help to improve drugs' performance.
Therefore, there is still a need to develop novel crystalline forms which are superior in one or more aspects compared with existing crystalline Form 1 and Form 2, so that these novel crystalline forms can meet strict requirements of industrial formulation production, and crystal properties or drug properties for future drug application.